

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        if (obstacleGrid[0][0] == 1)
            return 0;
        int m = obstacleGrid.size(), n = obstacleGrid[0].size();
        int dp[m][n];
        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
                dp[i][j] = 0;
        }

        for (int i = 0; i < m; i++)
        {
            if (obstacleGrid[i][0] == 0)
                dp[i][0] = 1;
            if (i > 0 && dp[i - 1][0] == 0)
                dp[i][0] = 0;
        }
        for (int i = 0; i < n; i++)
        {
            if (obstacleGrid[0][i] == 0)
                dp[0][i] = 1;
            if (i > 0 && dp[0][i - 1] == 0)
                dp[0][i] = 0;
        }
        for (int i = 1; i < m; i++)
        {
            for (int j = 1; j < n; j++)
            {
                if (obstacleGrid[i][j] == 1)
                    dp[i][j] = 0;
                else
                {
                    dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
                }
            }
        }
        return dp[m - 1][n - 1];
    }
};